First attempts to correct these two problems involved insulating the inside of the basement walls and covering the outer exterior foundation walls with some sort of bituminous or tar-like substance. Nevertheless, moisture tended still to penetrate these walls through cracks in the covering and because of the pressure of the surrounding water. Typically, drainage of ground water is accomplished by using a perforated pipe around the foundation which is surrounded by an aggregate substance such as gravel, the pipe leading off to some sort of drain.
More recently, it has been found that exterior insulation is more effective in preventing heat transfer from the surrounding ground into the dwelling or building. Also, it has been found that by using various materials with vertically oriented grooves or channels, water drainage to the footing is obtained by the channels or spaces. In the past, various attempts have been made to combine both insulating and drainage properties by using expanded polystyrene in various formations and configurations.
The product must be porous enough to provide sufficient insulating qualities but yet have sufficient compressive strength to resist crushing or deformation by ground fill and ground water pressure. The most significant problem which has plagued the new products is that caused by clogging of the vertically directed drainage channels by the backfill. Although proper backfill such as course aggregate should be used, today's high labour cost construction industry constructs many dwellings and buildings which are backfilled with whatever earth is nearby.
In the past few years, several attempts have been made to solve the problem of preventing the clogging of drainage channels in subterranean panels. Usually, these involve the use of two or more layers of materials. For example, in Canadian patent 1,158,054 (Pate), a water permeable synthetic resin strainer film is secured to the backing plate across the drainage channels to permit water to move to the channels without allowing dirt to enter the channels.
Again, in Canadian patent 1,202,190 (Sartor), a water pervious film is located at least on one side of the panel to prevent entry of the soil particles into the drainage grooves.
In Canadian patent 1,229,993 (Cogliano), a three-part insulating barrier was constructed comprising a porous planar sheet having on one face a plurality of spaced open continuous channels; a non-porous adhesive sheet adhered to an opposite side; and a porous woven or non-woven fibrous cloth located on the channels.
In Canadian patent 1,001,863 (Saito), an intermediate non-woven fabric layer having fibres of high denier interconnected at their cross-points by a binder is used. Surface layers are attached to both sides of the non-woven fabric layer. The surface layers are porous, but thinner and spiral springs are inserted which produce vertical channels.
In Canadian patent 1,249,135 (Cogliano), a water permable panel for the exterior surface of the foundation is disclosed and claimed. The first surface has a plurality of pores which are less than 0.1 millimeters in diameter. Water passes from this first major surface to a second major surface, the second major surface being a plurality of spaced open continuous vertical channels. The patent also suggests that a fibrous material in the form of fibrous mat could be applied to one side of the panel.
In Canadian patent 1,220,041 (Larsson), drainage channels are covered by a web-like material which prevents clogging by the soil.
Finally, in Canadian patent 1,199,188 (Gemmell), at least one water permeable web is used on one side of a cuspated sheet.
All of the aforementioned inventions more or less attempt to solve the clogging problem, but none of them were found to be sufficiently effective. Moreover, all of the inventions require the use of two or more layers or types of material bound together thereby creating high cost of production.
It is therefore an object of the present invention to provide a one-piece molded panel made of one material which has both insulating qualities and drainage properties. It is a further object of the invention to provide drainage channels which are not clogged by the surrounding earth, i.e. backfill.